The increasing usage of glass optical fiber waveguides in the communications field has revealed a corresponding increase in problems inherent in the glass as a transmission medium. One of the problems with a glass waveguide having a core of a high index of refraction and a cladding of a low index of refraction is signal distortion caused by the time delay occurring in the transmission of light through the core. One attempt to eliminate this problem is to provide a waveguide having a core of graded refractive index. In the profiled index fiber the wave components traveling in the region farthest from the center of the core are transmitted in a correspondingly lower index material and subsequently move with a greater velocity. The main purpose for the graded index core, therefore, is to provide pulse transmission through long length optical fibers with minimum signal distortion due to the time delay.
Methods currently available for providing a graded index core to optical fiber waveguides by the use of the appropriate range of materials are generally capable of providing the index gradient profile within a high degree of accuracy. The decrease of refractive index as a function of radial distance from the core center must follow a defined mathematical relationship for the graded fiber to be effective.
The purpose of this invention is to provide a means of producing an optical fiber waveguide having an effective graded index region with the use of two alternating materials.